Abstract: FR-PO802
Target Protein of Passive Heymann Nephritis and Its Role in the Mechanism of Proteinuria in Membranous Nephropathy (MN)
Session Information
- Glomerular Diseases: Inflammation and Immunology
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Diniz, Renan Gomes Mendes, University of Illinois Chicago, Chicago, Illinois, United States
- Singh, Ashok K., Hektoen Institute LLC, Chicago, Illinois, United States
Background
PHN is an established rat model of human MN. However, the target protein of PHN on the glomerulus is unknown and so is also the mechanism of proteinuria in PHN. Because of the striking similarity of the staining patterns of PHN and podocalyxin (PDX) we hypothesize that the target protein of the PHN antibody could likely be PDX. We examined this hypothesis by quantifying PDX in PHN rats at the time of proteinuria.
Methods
Rats were divided into one control (Cont) and six experimental (EX) groups. EX received 1 mL iv anti-gp600 antiserum to induce PHN while\ Cont received 1 mL of iv saline. PHN was confirmed by a strong glomerular capillary wall staining as seen by indirect immunofluorescence (IF). Rats were maintained by ad libitum access to food and water. Proteinuria was assessed at the end of each week until 6 weeks. At 6 weeks rats were euthanized and kidney was fixed with 10% buffered formalin. PDX was stained by IF and quantified using the Image J software. Data were statistically analyzed and compared using student t test and ANOVA.
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Results
Proteinuria was significantly elevated progressively from 1-6 weeks in EX (208mg/24h at 6 weeks). PDX staining in EX was significantly reduced by 25% at 6 weeks compared to Cont (36.6 ± 1.9 vs 48.4 ± 2.6 intensity units/glomerulus; p< 0,05) (Figure 1 below)
Conclusion
In conclusion, reduction of PDX in PHN suggests that the target of PHN antibody, and by analogy in MN, appears to be PDX, a podocytic protein that is known to be coupled with the actin cytoskeleton of the cell and therefore important in maintaining the foot process structure of the podocytes. We speculate that the reduction of PDX could be the mechanism of proteinuria in MN as its loss must disrupt the foot process architecture of the podocytes leading to the breakdown of the glomerular filtration.
Figure 1: PDX staining in Cont and EX: intensity units/glomerulus